Locally resonant metasurfaces for shear waves in granular media

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In this article the physics of horizontally polarized shear waves travelling across a locally resonant metasurface in an unconsolidated granular medium is experimentally and numerically explored.

• The metasurface is comprised of an arrangement of sub-wavelength horizontal mechanical resonators embedded in silica microbeads.
• The metasurface supports a frequency-tailorable attenuation zone induced by the translational mode of the resonators.
• The experimental and numerical findings reveal that the metasurface not only backscatters part of the energy, but also redirects the wavefront underneath the resonators leading to a considerable amplitude attenuation at the surface level, when all the resonators have similar resonant frequency.